Spatial Dependence of a Laser-Induced Shock Wave Mitigator Matrix: a Numerical Study

A laser shock wave (LSW) is a pressure wave in the range of gigapascals, duration in the order of nanoseconds, propagates at rates higher than Mach 1, and is induced by high power laser pulses. As an LSW propagates inside a solid, some physical material characteristics in the area of incidence are improved due to a residual compression stress field. However, since the LSW pressure reaches some tens of GPa, tensile stress damages the solid due to a spallation process if the material is fewer than 1 mm thick. A shock wave mitigation structure coupled to a solid reduces the LSW pressure due structure walls reflections, avoiding the spallation. In this work, a FEM simulation of LSW propagation in a 1 mm thick aluminum slab with a matrix of mitigating structures attached to the back is performed. The relationship among the induction area of the LSW, and the relative location of each mitigation structure in the matrix, has a direct influence on the pressure field distribution.